NavigationLink in SwiftUI not working anymore - ios

I´m creating an App and use NavigationLink in Swift/SwiftUI, but it doesn't work anymore. I don't now since when, but 2 or 3 weeks ago, all working fine. The NavigationLinks which already are in the code for longer, working fine. But today I've used new ones, and they don´t work. It looks in the Simulator and on a real device, if they are disabled or something. They are grey and you can't click on them or if you clicked on them, nothing happens. Is there any solution?
import SwiftUI
struct MedikamenteView: View {
var body: some View {
Form {
NavigationLink(
destination: ASSView(),
label: {
Text("ASS")
})
NavigationLink(
destination: AdrenalinView(),
label: {
Text("Adrenalin")
})
}
}
}
struct MedikamenteView_Previews: PreviewProvider {
static var previews: some View {
MedikamenteView()
}
}
And for example, this one is working fine:
import SwiftUI
struct RechtView: View {
var body: some View {
Form {
NavigationLink(
destination: ParagraphenView(),
label: {
Text("Paragraphen")
})
NavigationLink(
destination: AufklaerungEinwilligungView(),
label: {
Text("Die Aufklärung mit nachfolgender Einwilligung")
})
NavigationLink(
destination: NotSanGView(),
label: {
Text("Wichtiges aus dem NotSanG")
})
}
.navigationTitle("Recht")
}
}
struct RechtView_Previews: PreviewProvider {
static var previews: some View {
RechtView()
}
}

You have to use NavigationLinks inside NavigationView{}.
Without it NavigationLink wont work.
Try this:
import SwiftUI
struct MedikamenteView: View {
var body: some View {
NavigationView {
Form {
NavigationLink(
destination: ASSView(),
label: {
Text("ASS")
})
NavigationLink(
destination: AdrenalinView(),
label: {
Text("Adrenalin")
})
}
}
}
}
struct MedikamenteView_Previews: PreviewProvider {
static var previews: some View {
MedikamenteView()
}
}
Your second code sample might be loaded from previous view which has used NavigationView {}

I can see from the comments that you've found out it will only work in a NavigationView and are now wondering why. It only matters that your view is embedded in a NavigationView directly above it the View hierarchy. For example, this code would work:
struct FirstView: View {
var body: some View {
NavigationView {
NavigationLink(label: "Go to next view", destination: NextView())
}
}
}
struct NextView: View {
...
While this won't:
struct FirstView: View {
#State var modalPresented = false
var body: some View {
NavigationView {
Button("Show fullscreen cover"){
modalPresented = true
}
}
.fullScreenCover(isPresented: $modalPresented, content: SecondView())
}
}
struct SecondView: View {
var body: some View {
NavigationLink(label: "Go to next view", destination: NextView())
// Doesn't work because the view is in a fullScreenCover and therefore not a part of the NavigationView.
}
}

Related

How to run child function from parent?

I want to call childFunction() demo ChildView by pressing the button in the parent view.
import SwiftUI
struct ChildView: View {
func childFunction() {
print("I am the child")
}
var body: some View {
Text("I am the child")
}
}
struct ContentView: View {
var function: (() -> Void)?
var body: some View {
ChildView()
Button(action: {
self.function!()
}, label: {
Text("Button")
})
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Update:
Thanks #RajaKishan, it works, but I need it working also recursively
import SwiftUI
struct ContentView: View {
#State var text: String = "Parent"
var isNavigationViewAvailable = true
func function() {
print("This view is \(text)")
}
var body: some View {
VStack {
if isNavigationViewAvailable {
Button(action: {
function()
}, label: {
Text("Button")
})
}
if isNavigationViewAvailable {
NavigationView {
List {
NavigationLink("Child1") {
ContentView(text: "Child1", isNavigationViewAvailable: false)
}
NavigationLink("Child2") {
ContentView(text: "Child2", isNavigationViewAvailable: false)
}
NavigationLink("Child3") {
ContentView(text: "Child3", isNavigationViewAvailable: false)
}
}
}
}
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Maybe is is not the best looking example, but the question is, how to force the button to run function of it's child after user visited corresponding child.
Like, on start when user presses the button it prints "This view is Parent". After user comes to child1 the button press should print "This view is Child1" as so on. So, the function that button runs should be referenced from the last child.
Update:
In the end I wrote this solution.
Update:
I received feedback, asking me for clarification. No problem. I hope it'll help somebody.:)
Clarification:
I did not enclose the whole code, just used a simple example. But I needed this in my implementation of a tree-like generated menu: when each item in the menu has or does not have its children. Pressing on parent object user comes into child objects. And here I needed to be able to come back from a child object to parent, but call this dismiss function from the parent object. For this I used the following code and referred to this function to each parent object:
#Environment(\.presentationMode) var presentationMode
presentationMode.wrappedValue.dismiss()
You can create an object for a ChildView.
struct ChildView: View {
func childFunction() {
print("I am the child")
}
var body: some View {
Text("I am the child")
}
}
struct ContentView: View {
let childView = ChildView()
var body: some View {
childView
Button(action: {
childView.childFunction()
}, label: {
Text("Button")
})
}
}
EDIT : For the list, you can use the array of the model and call the destination function by index.
Here is the simple child-parent example.
struct ChildView: View {
var text: String
func childFunction() {
print("This view is \(text)")
}
var body: some View {
Text("I am the child")
}
}
struct ContentView55: View {
#State private var arrData = [Model(title: "Child1", destination: ChildView(text: "Child1")),
Model(title: "Child2", destination: ChildView(text: "Child2")),
Model(title: "Child3", destination: ChildView(text: "Child3"))]
var body: some View {
VStack {
Button(action: {
arrData[1].destination.childFunction()
}, label: {
Text("Button")
})
NavigationView {
SwiftUI.List(arrData) {
NavigationLink($0.title, destination: $0.destination)
}
}
}
}
}
struct Model: Identifiable {
var id = UUID()
var title: String
var destination: ChildView
}
Note: You need to index for the row to call child function.

Swift UI updating #EnvironmentObject prevent other update on #StateObject

I have the following view ModalView opened by by a parent view ParentView using a button in the toolbar
** Parent View **
import SwiftUI
struct ParentView: View {
#EnvironmentObject var environmentObject: MainStore
#State private var showCreationView = false
var body: some View {
NavigationView {
Text("ENV_OBJ Count: \(environmentObject.shoppingChartFullList.count)")
.navigationBarTitle(Text("Navigation Bar Title"))
.toolbar {
ToolbarItem(placement: .bottomBar) {
Button(action: { showCreationView = true }) {
Image(systemName: "plus")
}
.sheet(isPresented: $showCreationView, content: {
ModalView(showModelView: $showCreationView)
})
}
}
}
}
}
struct ParentView_Previews: PreviewProvider {
static var previews: some View {
ParentView().environmentObject(MainStore())
}
}
** Modal View **
import SwiftUI
struct ModalView: View {
#EnvironmentObject var environmentObject: MainStore
#Binding var showModelView: Bool
#State var newItem = ShoppingChartModel()
var body: some View {
Text(/*#START_MENU_TOKEN#*/"Hello, World!"/*#END_MENU_TOKEN#*/)
Button(action: {
environmentObject.shoppingChartFullList.append(newItem)
self.showModelView = false
}) {Text("Salva")}
}
}
struct ModalView_Previews: PreviewProvider {
static var previews: some View {
ModalView(showModelView: .constant(true)).environmentObject(MainStore())
}
}
** Main Store **
import Foundation
import SwiftUI
import Combine
final class MainStore: ObservableObject {
//An observable object needs to publish any changes to its data, so that its subscribers can pick up the change.
#Published var shoppingChartFullList: [ShoppingChartModel] = load()
}
The problem is that, action executed by the Save Button in the Modal View doesn't dismiss the modal (even if it correctly updates both the Boolean variable and the Env_Obj).
Seems to be related with the toolbar... in fact if I remove the Navigation View and the toolbar, putting the button directly in a stack ... it works...
In the Parent2View I remove the NavigationView and just configured the button directly in the view after the Text property. And it is working as expected.
import SwiftUI
struct ParentView2: View {
#EnvironmentObject var environmentObject: MainStore
#State private var showCreationView = false
var body: some View {
VStack {
Text("ENV_OBJ Count: \(environmentObject.shoppingChartFullList.count)")
Button(action: { showCreationView = true }) {
Image(systemName: "plus")
}
.sheet(isPresented: $showCreationView, content: {
ModalView(showModelView: $showCreationView)
})
}
}
}
struct ParentView2_Previews: PreviewProvider {
static var previews: some View {
ParentView2().environmentObject(MainStore())
}
}
UPDATE
Ok I finally found the solution. The issue is the toolbar. If the ParentView is modified as follow, all start working well
struct ParentView: View {
#EnvironmentObject var environmentObject: MainStore
#State private var showCreationView = false
var body: some View {
NavigationView {
Text("ENV_OBJ Count: \(environmentObject.shoppingChartFullList.count)")
.navigationBarTitle("Nav View Title")
.navigationBarItems(trailing:
Button(action: {
self.showCreationView.toggle()
})
{
Image(systemName: "plus")
.font(Font.system(.title))
}
)
}
.sheet(isPresented: $showCreationView) {
ModalView(showModelView: $showCreationView)
}
}
}
Thanks!
Cristian

How to switch to another view by each element's onTapGesture of a list in SwiftUI?

I tried to add a navigation view in the list as following. But it not works saying Result of 'NavigationView<Content>' initializer is unused
var body: some View {
GeometryReader { geometry in
VStack {
List {
ForEach(self.allItems){ item in
TaskRow(item: item)
.onTapGesture {
// TODO: switch to another view
NavigationView {
VStack {
Text("Hello World")
NavigationLink(destination: AnotherView()) {
Text("Do Something")
}
}
}
}
}
}
}
}
}
And AnotherView is a SwiftUI file as following:
import SwiftUI
struct AnotherView: View {
var body: some View {
VStack{
Text("Hello, World!")
}
}
}
struct AnotherView_Previews: PreviewProvider {
static var previews: some View {
AnotherView()
}
}
I have tried the solution in stackoverflow Switching Views With Observable Objects in SwiftUI and SwiftUI Change View with Button. They neither work in my situation.
How to switch to another view by onTapGesture of the list in SwiftUI like following:
var body: some View {
GeometryReader { geometry in
VStack {
List {
ForEach(self.allItems){ item in
TaskRow(item: item)
.onTapGesture {
// TODO: switch to another view
AnotherView()
}
}
}
}
}
}
You have to place whole your body into NavigationView.
Example
struct Item: Identifiable {
let id = UUID()
let name: String
}
struct ContentView: View {
var body: some View {
NavigationView {
List {
ForEach([Item(name: "A"), Item(name: "B")]) { value in
NavigationLink(destination: X(item: value)) {
Text(value.name)
}
}
}
}
}
}
struct X: View {
let item: Item
var body: some View {
Text(item.name)
}
}

SwiftUI: prevent View from refreshing when presenting a sheet

I have noticed that SwiftUI completely refresh view when adding sheetmodifier.
Let's say I have View that displays random number. I expect that this value would be independent and not connected to the sheet logic (not changing every time I open/close sheet), but every time sheet presented/dismissed Text is changing.
Is it supposed to work so?
Am I wrong that main point of #Sateis to update only connected Views but not all stack?
How can I prevent my View from refreshing itself when presenting a modal?
struct ContentView: View {
#State var active = false
var body: some View {
VStack {
Text("Random text: \(Int.random(in: 0...100))")
Button(action: { self.active.toggle() }) {
Text("Show pop up")
}
}
.sheet(isPresented: $active) {
Text("POP UP")
}
}
}
P.S. ContentView calls onAppear()/onDisappear() and init() only ones.
It needs to make separated condition-independent view to achieve behavior as you wish, like below
struct RandomView: View {
var body: some View {
Text("Random text: \(Int.random(in: 0...100))")
}
}
struct ContentView: View {
#State var active = false
var body: some View {
VStack {
RandomView()
Button(action: { self.active.toggle() }) {
Text("Show pop up")
}
}
.sheet(isPresented: $active) {
Text("POP UP")
}
}
}
In this case RandomView is not rebuilt because is not dependent on active state.
Asperi sad :
View is struct, value type, if any part of it changed then entire
value changed
He is absolutely right! But for that we have state properties. When the view is recreated, the value of state doesn't change.
This should work, as you expected
struct ContentView: View {
#State var active = false
#State var number = Int.random(in: 0 ... 100)
var body: some View {
VStack {
Text("Random text: \(number)")
Button(action: { self.active.toggle() }) {
Text("Show pop up")
}
}
.sheet(isPresented: $active) {
Text("POP UP")
}
}
}
What is the advantage? For simple things, the state / binding is the best solution, without any doubt.
import SwiftUI
struct SheetView: View {
#Binding var randomnumber: Int
var body: some View {
Button(action: {
self.randomnumber = Int.random(in: 0 ... 100)
}) {
Text("Generate new random number")
}
}
}
struct ContentView: View {
#State var active = false
#State var number = Int.random(in: 0 ... 100)
var body: some View {
VStack {
Text("Random text: \(number)")
Button(action: { self.active.toggle() }) {
Text("Show pop up")
}
}
.sheet(isPresented: $active) {
SheetView(randomnumber: self.$number)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Now you can dismiss the sheet with or without generating new random number. No external model is required ...

Dismiss NavigationView when Hidden SwiftUI [duplicate]

I was playing around with SwiftUI and want to be able to come back to the previous view when tapping a button, the same we use popViewController inside a UINavigationController.
Is there a provided way to do it so far ?
I've also tried to use NavigationDestinationLink to do so without success.
struct AView: View {
var body: some View {
NavigationView {
NavigationButton(destination: BView()) {
Text("Go to B")
}
}
}
}
struct BView: View {
var body: some View {
Button(action: {
// Trying to go back to the previous view
// previously: navigationController.popViewController(animated: true)
}) {
Text("Come back to A")
}
}
}
Modify your BView struct as follows. The button will perform just as popViewController did in UIKit.
struct BView: View {
#Environment(\.presentationMode) var mode: Binding<PresentationMode>
var body: some View {
Button(action: { self.mode.wrappedValue.dismiss() })
{ Text("Come back to A") }
}
}
Use #Environment(\.presentationMode) var presentationMode to go back previous view. Check below code for more understanding.
import SwiftUI
struct ContentView: View {
var body: some View {
NavigationView {
ZStack {
Color.gray.opacity(0.2)
NavigationLink(destination: NextView(), label: {Text("Go to Next View").font(.largeTitle)})
}.navigationBarTitle(Text("This is Navigation"), displayMode: .large)
.edgesIgnoringSafeArea(.bottom)
}
}
}
struct NextView: View {
#Environment(\.presentationMode) var presentationMode
var body: some View {
ZStack {
Color.gray.opacity(0.2)
}.navigationBarBackButtonHidden(true)
.navigationBarItems(leading: Button(action: {
self.presentationMode.wrappedValue.dismiss()
}, label: { Image(systemName: "arrow.left") }))
.navigationBarTitle("", displayMode: .inline)
}
}
struct NameRow: View {
var name: String
var body: some View {
HStack {
Image(systemName: "circle.fill").foregroundColor(Color.green)
Text(name)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
With State Variables. Try that.
struct ContentViewRoot: View {
#State var pushed: Bool = false
var body: some View {
NavigationView{
VStack{
NavigationLink(destination:ContentViewFirst(pushed: self.$pushed), isActive: self.$pushed) { EmptyView() }
.navigationBarTitle("Root")
Button("push"){
self.pushed = true
}
}
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
struct ContentViewFirst: View {
#Binding var pushed: Bool
#State var secondPushed: Bool = false
var body: some View {
VStack{
NavigationLink(destination: ContentViewSecond(pushed: self.$pushed, secondPushed: self.$secondPushed), isActive: self.$secondPushed) { EmptyView() }
.navigationBarTitle("1st")
Button("push"){
self.secondPushed = true;
}
}
}
}
struct ContentViewSecond: View {
#Binding var pushed: Bool
#Binding var secondPushed: Bool
var body: some View {
VStack{
Spacer()
Button("PopToRoot"){
self.pushed = false
} .navigationBarTitle("2st")
Spacer()
Button("Pop"){
self.secondPushed = false
} .navigationBarTitle("1st")
Spacer()
}
}
}
This seems to work for me on watchOS (haven't tried on iOS):
#Environment(\.presentationMode) var presentationMode
And then when you need to pop
self.presentationMode.wrappedValue.dismiss()
There is now a way to programmatically pop in a NavigationView, if you would like. This is in beta 5.
Notice that you don't need the back button. You could programmatically trigger the showSelf property in the DetailView any way you like. And you don't have to display the "Push" text in the master. That could be an EmptyView(), thereby creating an invisible segue.
(The new NavigationLink functionality takes over the deprecated NavigationDestinationLink)
import SwiftUI
struct ContentView: View {
var body: some View {
NavigationView {
MasterView()
}
}
}
struct MasterView: View {
#State var showDetail = false
var body: some View {
VStack {
NavigationLink(destination: DetailView(showSelf: $showDetail), isActive: $showDetail) {
Text("Push")
}
}
}
}
struct DetailView: View {
#Binding var showSelf: Bool
var body: some View {
Button(action: {
self.showSelf = false
}) {
Text("Pop")
}
}
}
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
#endif
It seems that a ton of basic navigation functionality is super buggy, which is disappointing and may be worth walking away from for now to save hours of frustration. For me, PresentationButton is the only one that works. TabbedView tabs don't work properly, and NavigationButton doesn't work for me at all. Sounds like YMMV if NavigationButton works for you.
I'm hoping that they fix it at the same time they fix autocomplete, which would give us much better insight as to what is available to us. In the meantime, I'm reluctantly coding around it and keeping notes for when fixes come out. It sucks to have to figure out if we're doing something wrong or if it just doesn't work, but that's beta for you!
Update: the NavigationDestinationLink API in this solution has been deprecated as of iOS 13 Beta 5. It is now recommended to use NavigationLink with an isActive binding.
I figured out a solution for programmatic pushing/popping of views in a NavigationView using NavigationDestinationLink.
Here's a simple example:
import Combine
import SwiftUI
struct DetailView: View {
var onDismiss: () -> Void
var body: some View {
Button(
"Here are details. Tap to go back.",
action: self.onDismiss
)
}
}
struct MainView: View {
var link: NavigationDestinationLink<DetailView>
var publisher: AnyPublisher<Void, Never>
init() {
let publisher = PassthroughSubject<Void, Never>()
self.link = NavigationDestinationLink(
DetailView(onDismiss: { publisher.send() }),
isDetail: false
)
self.publisher = publisher.eraseToAnyPublisher()
}
var body: some View {
VStack {
Button("I am root. Tap for more details.", action: {
self.link.presented?.value = true
})
}
.onReceive(publisher, perform: { _ in
self.link.presented?.value = false
})
}
}
struct RootView: View {
var body: some View {
NavigationView {
MainView()
}
}
}
I wrote about this in a blog post here.
You can also do it with .sheet
.navigationBarItems(trailing: Button(action: {
self.presentingEditView.toggle()
}) {
Image(systemName: "square.and.pencil")
}.sheet(isPresented: $presentingEditView) {
EditItemView()
})
In my case I use it from a right navigation bar item, then you have to create the view (EditItemView() in my case) that you are going to display in that modal view.
https://developer.apple.com/documentation/swiftui/view/sheet(ispresented:ondismiss:content:)
EDIT: This answer over here is better than mine, but both work: SwiftUI dismiss modal
What you really want (or should want) is a modal presentation, which several people have mentioned here. If you go that path, you definitely will need to be able to programmatically dismiss the modal, and Erica Sadun has a great example of how to do that here: https://ericasadun.com/2019/06/16/swiftui-modal-presentation/
Given the difference between declarative coding and imperative coding, the solution there may be non-obvious (toggling a bool to false to dismiss the modal, for example), but it makes sense if your model state is the source of truth, rather than the state of the UI itself.
Here's my quick take on Erica's example, using a binding passed into the TestModal so that it can dismiss itself without having to be a member of the ContentView itself (as Erica's is, for simplicity).
struct TestModal: View {
#State var isPresented: Binding<Bool>
var body: some View {
Button(action: { self.isPresented.value = false }, label: { Text("Done") })
}
}
struct ContentView : View {
#State var modalPresented = false
var body: some View {
NavigationView {
Text("Hello World")
.navigationBarTitle(Text("View"))
.navigationBarItems(trailing:
Button(action: { self.modalPresented = true }) { Text("Show Modal") })
}
.presentation(self.modalPresented ? Modal(TestModal(isPresented: $modalPresented)) {
self.modalPresented.toggle()
} : nil)
}
}
Below works for me in XCode11 GM
self.myPresentationMode.wrappedValue.dismiss()
instead of NavigationButton use Navigation DestinationLink
but You should import Combine
struct AView: View {
var link: NavigationDestinationLink<BView>
var publisher: AnyPublisher<Void, Never>
init() {
let publisher = PassthroughSubject<Void, Never>()
self.link = NavigationDestinationLink(
BView(onDismiss: { publisher.send() }),
isDetail: false
)
self.publisher = publisher.eraseToAnyPublisher()
}
var body: some View {
NavigationView {
Button(action:{
self.link.presented?.value = true
}) {
Text("Go to B")
}.onReceive(publisher, perform: { _ in
self.link.presented?.value = false
})
}
}
}
struct BView: View {
var onDismiss: () -> Void
var body: some View {
Button(action: self.onDismiss) {
Text("Come back to A")
}
}
}
In the destination pass the view you want to redirect, and inside block pass data you to pass in another view.
NavigationLink(destination: "Pass the particuter View") {
Text("Push")
}

Resources